In the preparation of liquid treatment compositions, it is always an aim to improve technical capabilities thereof and aesthetics. The present invention relates to the improvement in the traditionally transparent or opaque aesthetics of liquid compositions. The present invention relates to liquid compositions comprising optical modifiers that are capable of refracting light such that the compositions appear pearlescent.
Pearlescence can be achieved by incorporation and suspension of a pearlescent agent in the liquid composition. Pearlescent agents include inorganic natural substances, such as mica, fish scales, bismuth oxychloride and titanium dioxide, and organic compounds such as metal salts of higher fatty acids, fatty glycol esters and fatty acid alkanolamides. The pearlescent agent can be acquired as a powder, suspension of the agent in a suitable suspending agent or where the agent is a crystal, it may be produced in situ.
Detergent compositions and pearlescent dispersions comprising pearlescent agent fatty acid glycol ester are disclosed in the following art; U.S. Pat. No. 4,717,501 (to Kao); U.S. Pat. No. 5,017,305 (to Henkel); U.S. Pat. No. 6,210,659 (to Henkel); U.S. Pat. No. 6,835,700 (to Cognis). Liquid detergent compositions containing pearlescent agent are disclosed in U.S. Pat. No. 6,956,017 (to Procter & Gamble). Liquid detergents for washing delicate garments containing pearlescent agent are disclosed in EP 520551 B1 (to Unilever). Having put effort and expense into improving the aesthetics of a composition, the Applicant preferably packages the ensuing composition in a transparent or translucent package, be it for example a bottle, box, tub or water-soluble film. However some ingredients of the composition that are essential or at least preferred for performance are sensitive to light. Packaging the composition in a transparent or translucent package increases the risk or destabilization of these light-sensitive ingredients. It is important to protect these light sensitive ingredients as far as possible in order to maintain stability of the product, aesthetics and performance for as long as possible. Especially since a product may remain in storage or on shelf for some time, potentially a period of several months.
Bismuth oxy chloride, a pearlescent agent has previously been described as also being sensitive to light Ke-Lei Zhang et al., Applied Catalysts: Environmental 68 (2006) pp 125-129. In this report Bismuth oxy chloride is reported to be a photocatalyst which can decompose dyes upon exposure to light.
Despite the above, it has surprisingly been found that compositions comprising an inorganic pearlescent agent exhibit improved light-sensitive ingredient stability.